Looking For A Nest

I've not seen one of these before: a spiny softshell turtle. I had to look twice because it was no where near the lake, presumably looking for a suitable nesting site. Not sure pebbles would be a great choice and I went back later to find it had gone without leaving any signs. I'd say the shell was 12-14 inches in length, so a big one. Apparently males are smaller.

Finding a good angle was an issue. I tried side on, but this angle shows off the shell markings. I didn't want to get any closer. I also took a few shots to focus stack, but stuck with a single frame in the end.